>TeX takes as much care as Unicode of good typography
[...]
>TeX goes even beyond Unicode at least for one interesting special
>character: TeX distinguishes between normal spaces and spaces after a
>sentence. The latter are allowed to grow a bit larger during paragraph
>formatting (unless the \frenchspacing option is activated which
>prohibits this), and according to at least US typewriter rules are
>represented by a double space on typewriters (not so Europe).

Good gods, what a horrible "solution". The _problem_ is that when they
learned to type people (mostly North Americans) didn't learn the detail
that there really _aren't_ supposed to be two spaces after a full stop, it
is only TYPED there with MECHANICAL TYPEWRITERS on PAPER to help someone
else actually set the page. In the modern world of electronic publishing,
whether on one's own desktop or another's,

>I wonder, whether it would be a good idea to add such an end-of-sentence
>space to Unicode.

Try it if you dare and if you really like invective.

>I understand that it is primarily an artifact of US
>typographic tradition and that Europeans tend not to make any
>distinction between spaces that terminate sentences.

No, it's an artifact of bad training codified by someone who should have
known better.